This invention concerns an assembly system for composite material and metal, making the use of composite materials for transportation of corrosive and/or abrasive fluids possible at static pressures of up to 150 MPa.
In particular, the invention facilitates insertion between metal tubes (through which a fluid under very high pressure is flowing) of a composite tube element which may be part of a sensor designed to measure various properties of the fluid (viscosity, flow-rate, density, etc.)
One of the problems recognized in the previous state of the art was the difficulty of realizing composite material/metal joints able to withstand very high pressures for long periods of time. The invention solves this problem.
One most important application is to sensors used in oil and oil-related industry, used, as is well-known, to measure the properties (viscosity, density, rheology, etc.) of fluids piped under very high pressure, which may be corrosive (acids) and/or highly abrasive (cement slurries).
Using the invention, a metal joining piece with a projecting collar at the end in contact with the composite material and a high pressure joining piece at the other end is placed between the composite material and the metal tube.
One of the invention's essential characteristics is the projecting collar (2) around which the various layers of composite material are placed in the accustomed manner, by winding.
The advantage of this structure is that normal winding of the composite material is made possible while, for the first time, resistance to tensile and torsional stresses occurring between the metal tube (and the metal joining piece) on the one hand, and the composite tube on the other, is ensured.
Thus, risk of distortion, leaks and fractures, which are common in attempts made in the previous state of the art, is eliminated.
Considering the working pressures, it is evident that this advantage is quite decisive.
Within oil and oil-related industry, the drawbacks of the previous state of the art have even more serious consequences (any interruption of work on a line involves serious risks bad well treatment, bad cement placement; with sometimes unsalvageable consequences).